Coating composition

ABSTRACT

The invention relates to a coating composition comprising (i) a supporting medium, and (ii) a plurality of cellulose particles, having an average dry particle size of less than 10 μm, dispersed in the supporting medium, excluding aqueous coating compositions adapted for application to paper. The invention also relates to a coating composition comprising (i) a supporting medium, and (ii) a plurality of cellulose particles, having an average dry particle size of less than 10 μm, dispersed in the supporting medium in an amount of less than about 5 g/L. The coating compositions of the invention form coatings which have useful thermal properties.

TECHNICAL FIELD

The present invention relates to coating compositions which formcoatings which have useful thermal properties.

BACKGROUND ART

It is well understood that heat can be transmitted from one place toanother by three mechanisms, namely radiation, conduction andconvection.

The benefits of insulating buildings and other structures have long beenunderstood. Typically, buildings and other structures are insulatedusing poor thermal conductive materials such as fibreglass and wool.These materials are typically used in the walls and ceilings ofstructures to retard the transfer of heat into the structure duringwarmer months, and to retard the transfer of heat out of the structureduring cooler months.

A number of attempts have been made to develop paints that effectivelyretard the transfer of heat through a surface to which the paint hasbeen applied. For example, materials such as sodium bicarbonate andsteric acid, potassium titanate fibres, glass frit, aluminium flakes,vermiculite, perlite and glass wool have all been considered as possibleadditives to paint to produce thermally insulating paints. Each of theseadditives has been of only limited value in producing thermallyinsulating paints. Further, the inclusion of such additives in paintoften detracts from the desirable properties of paint, such as its easeof application to surfaces, and the aesthetic appearance of the paintcoating.

One paint product which has been described as having good thermalinsulative properties is described in the specification for Australianpatent no. 601148. That specification describes a high build paintcoating formed from a composition comprising a hardenable liquid paintbase, silica particles and bagasse particles, wherein the silica andbagasse particles comprise up to 60 percent by weight of the mixture.This coating is described as being effective in maintaining a reducedtemperature in the interior of a structure subject to radiant heatcompared to an equivalent unpainted structure. The described compositiondoes however suffer from a number of disadvantages. The describeddimensions of the bagasse particles included in the composition make thecomposition difficult to apply to a surface and may have undesirableeffects on the appearance of the paint coating. Further, the largeparticle sizes of the silica and bagasse particles used in someembodiments of the invention result in coatings which are likely tosuffer from fungal problems. The large particle sizes result in a verythin layer of the other components of the composition over the silicaand bagasse particles in the coating formed from the composition. Insome embodiments, this thin layer does not provide adequate protectionfrom moisture reaching the bagasse particles thereby allowing the growthof fungi. Further, the required thickness of the paint coating to renderit effective make the composition an unsuitable product for use inapplications where thinner coatings of paint are required, such asinterior and exterior house paints and automotive finishes.

The specification for Australian patent application no. 10487/92describes the use of microcrystalline cellulose particles having anaverage particle size of 1 to 10 μm in paper coating compositions. Thepaper coating compositions described in that specification comprise theparticles of cellulose in an aqueous suspension. The paper coatingcompositions described in that specification are said to be useful forenhancing the performance of commercial optical brighteners. There is nosuggestion or indication in that document that coatings formed from thecompositions disclosed in that document may have an effect in alteringthe transfer of heat through paper or any other surface to which thecoating composition is applied.

DISCLOSURE OF THE INVENTION

The inventors have surprisingly found that coating compositionscontaining cellulose particles having an average dry particle size ofless than 10 microns (10 μm) dispersed throughout the coatingcomposition produce coatings which have useful thermal properties.

In one aspect, the present invention provides a coating compositioncomprising

(i) a supporting medium, and(ii) a plurality of cellulose particles, having an average dry particlesize of less than 10 μm, dispersed in the supporting medium in an amountof less than about 10 g/L, excluding aqueous coating compositionsadapted for application to paper.

The cellulose particles can be obtained by any means known in the artfor obtaining cellulose particles having an average dry particle size ofless than 10 μm. The cellulose particles can be obtained from cellulosefibres, cellulose derivatives or a combination of both. The celluloseparticles can be derived from suitable natural materials such as radiatapine and macadamia shells. Such cellulose particles can be micronised toachieve the desired average dry particle size. Preferably, the celluloseparticles comprise particles of microcrystalline cellulose.

Commercially available microcrystalline cellulose particles which may beused in the coating composition according to the present inventioninclude Avicel 1.02330.0000 produced by Merck Australia Pty Ltd for thinfilm chromatography. This product consists of microcrystalline celluloseparticles present in the form of rod shaped particles having an averagesize of 4×25 μm. When added to a liquid supporting medium and dispersedunder high shear, these particles break up into particles having anaverage dry particle size of approximately 4×7 μm.

In some embodiments of the invention, the cellulose particles have anaverage dry particle size of less than 1 μm.

Preferably, substantially all of the cellulose particles havesubstantially identical particle size, that is, particle sizes within 20percent of the average particle size in the composition.

The amount of cellulose particles in the coating composition is lessthan about 10 g/L, typically in the range 0.0002 g/L to 10 g/L.Typically, the amount of cellulose particles in the coating compositionis less than 5 g/L. A coating composition according to the presentinvention may, for example, contain cellulose particles in an amountwithin the range 0.01 g/L to 0.1 g/L, or within the range 0.0002 g/L to0.01 g/L.

Typically the supporting medium is a liquid medium which when applied toa surface forms a coating on the surface. As used herein, the term“liquid” is taken to include amorphous, gelatinous, fluid and pourablesubstances.

Typically, the supporting medium is a liquid paint based compositionwhich when applied to a surface and dried forms a dry paint coating onthe surface. A liquid paint based composition typically consists of apolymer, solvents, various additives and often pigments. In someembodiments of the invention, a chemical reaction crosslinking thepolymer in the liquid paint based composition occurs when the coatingcomposition is applied to a surface and dried. Paint based compositionstypically contain polymers such as polyesters, alkyds, acrylics,polyurethanes, epoxies, vinyls, polyamides, silicones, or combinationsof these polymers. Solvents typically used in liquid paint basedcompositions include water or organic or inorganic solvents.

Suitable liquid supporting media can also be a non-paint basedcomposition that can solidify to form a coating on a surface. Examplesof such media include polymeric compounds (e.g. polyethylene,poly(vinylchloride), polypropylene, nylons), or resin or papercompositions.

Suitable liquid supporting media can also be a medium that does notsolidify when applied to a surface, but rather forms a gelatinous orviscous liquid coating on the surface.

The supporting medium can also be a media adapted for forming freestanding coating compositions, such as film-like materials, which can beapplied to a surface to form a coating on the surface. For example, aclear plastic film adapted for application to glass, such as a window,to form a coating on the glass.

The supporting medium may also be an adhesive. For example, thesupporting medium may be an adhesive layer applied to a surface of awindow film to bond the window film to glass or to further sheets ofwindow film in the case of a multi-layered window film.

The supporting medium may be a conventional coating composition, such asa conventional paint based coating composition.

The cellulose particles may be dispersed in the supporting medium bymeans known in the art. When the supporting medium is a liquid, such asa liquid paint based composition, the cellulose particles are typicallydispersed under high shear, typically using equipment known as a HighShear Disperser. When the supporting medium is a media adapted forforming a free standing coating composition, such as a plastic film, thecellulose particles are typically dispersed in the supporting mediaduring the manufacture of the coating composition.

The coating compositions according to the present invention may beapplied to a surface to form a coating on the surface by any means knownin the art for applying similar coating compositions not containingcellulose particles to a surface to form a coating on the surface.

When the supporting medium is a conventional coating composition, thecoating composition according to the present invention may be applied tothe surface of articles or structures to form a coating on the surfaceusing standard techniques known in the art for applying the conventionalcoating composition to a surface to form a coating on the surface. Forexample, when the supporting medium is a conventional paint basedcomposition, the coating composition of the present invention may bepainted on the surface of an article or structure and dried to form acoating on the surface.

The coating composition may be adapted for forming a coating on anatural or artificial material. In various embodiments of the invention,the coating composition is adapted for forming a coating on a plasticmaterial, a fabric, a fibre, a film, a ceramic, a composite material,concrete, wood, human or animal skin or metal or metal alloy.

In some embodiments, the coating composition is adapted for forming acoating on a portion of an article or structure such as a vehicle,building, transportable container or a storage tank. In someembodiments, the coating composition is adapted for forming a coating onwalls, roof or other parts of a building. Similarly, in some embodimentsof the invention, the coating composition is adapted for forming acoating on a surface of an automobile.

In a preferred embodiment, the coating composition is a paint basedcomposition adapted to dry to form a dry film coating of a thickness ofbetween 2 and 250 μm when applied to a surface. In the case of paintbased compositions adapted for application to the interior or exteriorof structures such as buildings, the paint based composition ispreferably adapted to dry to a dry film thickness of between 35 and 120μm. In the case of paints for use as automotive finishes, the paintbased composition is preferably adapted to dry to a thickness of betweenabout 20 and 70 μm.

In another aspect, the present invention provides a coating formed froma coating composition according to the present invention.

The coating can be a solid material, a film-like material or agelatinous or viscous liquid material.

In a further aspect, the present invention provides an article orstructure wherein at least one surface of the article or structure hasapplied to it a coating formed from a coating composition according tothe present invention.

In various embodiments of the invention, a coating according to thepresent invention may form one or more layers of a multi-layer coating.For example, a coating according to the present invention may form anundercoat or first coating layer on a surface, with a top coat formedover the undercoat layer using a coating composition not containingcellulose particles.

The present inventors have surprisingly found that the coatingsaccording to the present invention have useful thermal properties.

The inventors have found that when a coating according to the presentinvention is applied to a surface, and the coated surface is exposed toradiant heat, the coating reduces or increases the heat transferredthrough the surface compared to similar coatings formed from coatingcompositions not containing particles of cellulose.

For example, when a coating according to the present invention isapplied to the external surfaces of a metal structure, and the structureis exposed to radiant heat, the coating insulates the structuremaintaining the interior of the structure at a temperature significantlylower than that of an equivalent structure having a coating formed froma similar coating composition not containing particles of cellulose, oran equivalent structure having no coating on the external surfaces.Further experiments undertaken by the inventors also suggest that if theambient temperature outside the structure falls below the internaltemperature of the structure, the coating on the external surface of thestructure serves to facilitate the transmission of heat out of thestructure at a more rapid rate than an equivalent structure having acoating on the external surfaces formed from a similar coatingcomposition not containing cellulose particles, or an equivalentstructure having no coating on the external surfaces. This is aparticularly useful feature for structures such as buildings containingheat generating machinery, such as electric motors, welding bays or thelike.

When the coating is a plastic film applied to a glass surface such as awindow, and the coated surface exposed to radiant heat, the inventorshave found that the coating increases the heat transferred through thesurface compared to a similar plastic film coating not containingcellulose particles.

The inventors have also surprisingly found that the smaller the averageparticle size of the cellulose particles dispersed in the coatingcomposition, the lower the proportion of cellulose particles required tobe added to the composition to maintain the useful thermal properties ofcoatings formed from the composition. For example, a paint coating of200 μm dry film thickness formed from a liquid paint based compositionaccording to the present invention containing 1 g/L of microcrystallinecellulose particles has similar thermal properties to a paint coatingformed from a composition containing about 15 g/L of micronisedcellulose particles having average size of about 16 μm in a coating of200 μm dry film thickness. Experiments by the inventors have alsodemonstrated that the thermal properties of coatings formed from coatingcompositions containing cellulose particles having an average dryparticle size of less than 10 μm is retained as the proportion ofcellulose particles in the composition is decreased from 1 g/L to 0.0002g/L.

BRIEF DESCRIPTION OF DRAWINGS

Hereinafter by way of example only, preferred embodiments of theinvention will now be described with reference to the accompanyingdrawings in which:

FIG. 1 is a cross-sectional view (not to scale) of the samples tested inthe experiments described herein;

FIG. 2 is a diagrammatic view of a test apparatus;

FIG. 3 is an enlarged cross-sectional view of the box 30 depicted inFIG. 2;

FIG. 4 is a temperature versus time graph of the non-exposed surfaces ofSamples A, B and C tested in the apparatus depicted in FIGS. 2 and 3wherein radiant heat was applied to the surface of Samples A and Bhaving the coating (the coating being a water-based acrylic paint);

FIG. 4 a is a temperature versus time graph of the non-exposed surfacesof Samples A, B and C tested in the apparatus depicted in FIGS. 2 and 3wherein radiant heat was applied to the surface of Samples A and B nothaving the coating;

FIG. 4 b is a temperature versus time graph of the non-exposed surfacesof Samples C, D and E tested in the apparatus depicted in FIGS. 2 and 3wherein radiant heat was applied to the surface of Samples D and E nothaving the coating (the coating being a water-based acrylic paint);

FIG. 4 c is a temperature versus time graph of the non-exposed surfacesof Samples C, D and E tested in the apparatus depicted in FIGS. 2 and 3wherein radiant heat was applied to the surface of Samples D and Ehaving the coating;

FIG. 4 d is a temperature versus time graph of the non-exposed surfacesof Samples C, F and G tested in the apparatus depicted in FIGS. 2 and 3wherein radiant heat was applied to the surface of Samples F and Ghaving the coating (the coating being a water-based acrylic paint);

FIGS. 5-10 depict temperature versus time graphs of the non-exposedsurfaces of Samples A and C and a third sample (the Test Sample) testedin the apparatus depicted in FIGS. 2 and 3 wherein radiant heat wasapplied to the surface of Sample A and the Test Sample having thecoating (the coating being a water-based acrylic paint);

FIGS. 11 & 12 are temperature versus time graphs of the non-exposedsurfaces of Samples A and C and a third sample (the Test Sample) testedin the apparatus depicted in FIGS. 2 and 3 wherein radiant heat wasapplied to the surface of Sample A and the Test Sample having thecoating (the coating on the Test Sample being a polyurethane paint-2pack, polyester base and isocyanate catalyst);

FIG. 13 is a temperature versus time graph of the non-exposed surfacesof three samples tested in the apparatus depicted in FIGS. 2 and 3wherein radiant heat was applied to the surface of the samples havingthe coating (the coating being a coil coating of the plastisol type).

FIGS. 14 & 15 are temperature versus time graphs of the non-exposedsurfaces of Sample A and a second sample (the Test Sample) tested in theapparatus depicted in FIGS. 2 and 3 wherein radiant heat was applied tothe surface of the samples having the coating (the coating on the TestSample being a water based ink);

FIG. 16 is a temperature versus time graph of the non-exposed surfacesof two samples tested in the apparatus depicted in FIGS. 2 and 3 whereinradiant heat was applied to the surface of the samples having thecoating (the coating being a window film);

FIG. 17 is a temperature versus time graph of the non-exposed surfacesof two samples having a foam coating and a third sample having nocoating tested in the apparatus depicted in FIGS. 2 and 3 whereinradiant heat was applied to the surface of the samples having the foamcoating (the coating being a fire fighting foam);

MODES OF CARRYING OUT THE INVENTION

A cross-sectional view of the samples used in the experiments describedherein is shown in FIG. 1. The sample 10 comprises a coating 11 appliedto a surface of a substrate 12.

In all of the experiments described herein, other than the experimentinvolving window film coatings applied to glass sheets, the substrate 12consisted of a steel plate of dimensions 200×300×0.9 mm. On one 200×300mm surface of the steel substrate 12, a coating 11 was formed. Theopposite 200×300 mm surface 13 of the steel substrate 12 was coated witha thin layer of conventional black paint. Such samples can be consideredrepresentative of coatings applied to structures such as buildings andvehicles.

To allow a comparison of the performance of coatings formed from coatingcompositions according to the present invention, experiments wereinitially undertaken by the present inventors on comparison or referencesamples. A coating composition was prepared by adding celluloseparticles at a ratio of 55 grams per litre to a water base acrylic paintcomposition and dispersed under high shear. The cellulose particles inthis composition had an average particle size of 55 cm. The mainreference sample (Sample A) comprised a steel plate of the dimensionsreferred to above. On one of the 200×300 mm surfaces of the steel platea coating was formed from the prepared coating composition. Thethickness of the paint coating on drying of the paint was measured to be270 μm. As indicated above, the opposite 200×300 mm surface of the steelplate was painted with a thin layer of conventional black paint.

The reference sample and the other samples described herein were testedin the apparatus depicted in FIGS. 2 and 3.

The test apparatus comprises a box 30 acting as a heat sink and havingwalls 31 and a base 32. The walls 31 and base 32 are thermally insulatedwith polystyrene sheets to prevent heat loss and to also lessen thelikelihood of external condensation. The box 30 contains column blocksof ice 43 laid in a lattice like fashion to maximize the absorption ofheat within the box 30. Two multi-speed rotating blade fans 44 are alsoavailable to provide circulation and give a wind chill factor ifdesired.

The box 30 also has a top surface 33 having three identical rectangularholes 34 formed therein. Each hole is surrounded by a jig 35 whichsupport a sample 36, such as the Sample A described above, to be testedby the apparatus. In FIG. 2 the right end rectangular hole 34 isconcealed by the samples 36.

Above each of the samples 36 is mounted a light source 37 which providesa source of thermal irradiation to the top surface of the sample 36. Thelight sources 37 are suspended from a beam 38 which can be moved up anddown to allow corresponding movement in the position of the lightsources 37 above the samples 36.

Each light source comprises a 100 W tungsten lamp under the control ofan electric circuit (not depicted). A thyristor control (not depicted)is provided in the electric circuit to allow the brightness of the lightsources 37 to be adjusted as required.

Attached to the lower surface 45 of each sample 36 is a Type Jthermocouple 38. The thermocouple 38 is attached to the lower surface 45by means of double-sided adhesive tape. The position of the thermocouple38 is set by the use of a template which ensures the thermocouple 38 ispositioned in the center of the sample 36 directly below the center ofthe light source 37.

The thermocouple leads 39 extend out past a foam rubber strip sealingthe box 30 and extend to an electronic cold junction 41 which is, inturn, connected to a computer 42. The computer 42 stores and displaysthe temperatures measured at the lower surface of each sample 36 by eachthermocouple 38.

During the original set-up and calibration of the test apparatus, threepolished aluminum sheets having a thickness of approximately 0.9 mm weremounted in the jigs 35 and tested to balance the output from the threethermocouples 38.

A normal experiment was conducted in the following manner:

(i) three samples 36 were selected for testing and then marked by atemplate to allow accurate location of the thermocouple 38 on theopposite 200×300 mm surface of sample to the 200×300 mm surface to beirradiated by the light source 37;(ii) a thermocouple 38 was then attached using double-sided adhesivetape to each sample 36 on the opposite 200×300 mm surface of the sampleto the 200×300 mm surface to be irradiated by the light source 37;(iii) the three samples 36 were then brought to ambient room temperatureby placing them in front of a rotary fan for several minutes;(iv) the three samples 36 were then rapidly loaded into the jigs 35 sothat the surface of the samples 36 to be irradiated by the light sources37 faces the light source, and the light sources 37 switched on;(v) the computer program was then started and the temperature of thelower surface 45 of each sample 36 (i.e. the 200×300 mm surface oppositeto the 200×300 mm surface irradiated by the light source 37) was storedand displayed by the computer 42.

In most experiments, the light source was turned off after a fewminutes, and the temperature of the lower surface 45 of each sample 36was stored and displayed by the computer 42 while the light source wason and for a period of time after the light source was turned off.

In a first experiment, a reference sample (Sample A) as described abovewas compared with a similar sample (Sample B) having a paint coatingformed from the same water based acrylic paint composition used forSample A but not containing cellulose particles, and a sample consistinga steel plate of dimensions 200×300×0.9 mm painted with a thin layer ofconventional black paint on both of the 200×300 mm surfaces (Sample C).A thermocouple was attached to each of the samples such that the paintcoating 11 of Samples A and B was irradiated by the light source 37 whenthe samples were placed in the test apparatus.

The samples were appropriately placed in the test apparatus and thelight sources 37 illuminated. The temperature measured by thethermocouples 38 was recorded by the computer 42.

The results of the first experiment are depicted in FIG. 4. The resultsindicate that the temperature of the unexposed surface of Sample A onlyreached a maximum of approximately 37° C. whereas the temperature of theunexposed surface of Sample B and Sample C reached a maximum temperatureof approximately 42° C. and 67° C., respectively. These resultsdemonstrate that the coating formed from the coating compositioncontaining the cellulose particles reduced the magnitude of heattransferred through the sample to which the coating was applied comparedto the coating formed from the coating composition not containingcellulose particles.

In a further experiment, the same samples as tested above (ie: SamplesA, B and C) were tested with the thermocouples 38 attached instead tothe coating layer of Samples A and B and the samples placed in the testapparatus such that the light sources irradiated the surface of SamplesA and B coated with a thin layer of black paint. The increase intemperature measured by the thermocouples 38 in this further experimentis depicted in FIG. 4 a. The results indicate that the temperature ofthe unexposed surface of Sample A reached a maximum of approximately 74°C. whereas the temperature of the unexposed surface of Sample B andSample C each reached a maximum temperature of approximately 66° C.

The results depicted in FIGS. 4 and 4 a demonstrate that the magnitudeof heat transfer through the sample to which a coating containingcellulose particles has been applied is dependent on which surface ofthe sample is irradiated by the thermal radiation provided by the lightsources 37. When the coated surface of Samples A and B was irradiated bythe thermal radiation, the heat transfer through Sample A was less thanSamples B and C. When the surface of Samples A and B coated with a thinlayer of black paint was irradiated by the thermal radiation, the heattransfer through Sample A was higher than the heat transfer throughSamples B and C.

Similar results were observed by the inventors in a further series ofexperiments testing two steel plates, one coated on one 200×300 mmsurface with a non-white paint coating formed from a liquid paint basedcomposition having dispersed therethrough cellulose particles (at 55g/L, 50 μm average diameter) (Sample D) and one coated on one 200×300 mmsurface with a paint coating formed from the same paint basedcomposition but not containing cellulose particles (Sample E). Thecolour of the paint was a brown/green colour known in the trade as“environmental green”. As indicated above, the other 200×300 mm surfaceof both samples was coated with a thin layer of conventional blackpaint. The results of the experiment when heat was applied to thesurface of Samples D and E coated with a thin layer of black paint aredepicted in FIG. 4 b. These results again indicate that Sample D havingthe coating incorporating the cellulose particles exhibited a higherdegree of heat transfer than Sample E and Sample C when heat was appliedto the surface of Samples D and E coated with a thin layer of blackpaint. The results depicted in FIG. 4 c for when the coated surface ofeach of Sample D and Sample E were irradiated reveal, in contrast, thatthe heat transfer was lower for Sample D than Sample E or Sample C.

In a further experiment, 0.1 g/L microcrystalline cellulose particles(Avicel 1.02330.0000 produced by Merck Australia Pty Ltd) was added to awhite water-based acrylic paint coating composition, and dispersed underhigh shear breaking the cellulose particles into particles having anaverage dry particle size of less than 10 μm. A sample having a coatingformed from this coating composition (Sample F) was compared withanother sample having a coating formed from the same paint coatingcomposition but without the addition of cellulose particles (Sample G).The results of the experiment when heat was applied to the coatedsurface of Sample F and Sample G is depicted in FIG. 4 d. The resultsdepicted in FIG. 4 d demonstrate that the heat transfer for Sample F waslower than that for Sample G.

The performance of Sample A was the benchmark used by the presentinventors against which samples having coatings formed from coatingcompositions according to the present invention were compared.

Using the same paint base (water based acrylic) as Sample A a series ofcoating compositions according to the present invention incorporatingthe proportions of microcrystalline cellulose particles indicated inTable 1 were prepared. The coating compositions were prepared by mixingmicrocrystalline cellulose particles (Avicel 1.02330.0000 produced byMerck Australia Pty Ltd) with the paint base, and dispersing thecellulose particles under high shear breaking the cellulose particlesinto particles having an average dry particle size of less than 10 μm.Samples having a coating of the dry thickness indicated in Table 1 wereprepared using these coating compositions (the Test Samples), and theTest Samples were tested together with Samples A and C as describedabove, with the heat applied to the surface of the Test Sample havingthe coating and the surface of Sample A having the coating. Thetemperatures measured by the thermocouples attached to some of thesesamples in the test apparatus 30 are depicted in FIGS. 5-10.

The relative inefficiency of these samples in comparison to thereference sample (Sample A) was calculated as the difference between themaximum temperature reached for the sample and that reached for Sample Adivided by the maximum temperature reached for Sample C expressed as apercentage. A negative number means the sample was more efficient inretarding the transfer of heat through the sample than Sample A. Therelative inefficiency of the samples is set out in Table 1.

TABLE 1 Thickness Relative Sample of coating Mix ratio inefficiency CodeFig. (μm) (g/L) (%) 964 110 10 1.525 965 5 110 9 −1.571 966 110 8 −2.067967 110 7 −1.246 968 110 6 0.363 969 6 110 5 −2.615 970 110 4 −1.178 971110 3 −3.026 972 110 2 −0.015 973 110 1 −2.531 974 90 0.8 4.517 975 7 900.6 −2.384 976 90 0.4 −0.471 986 110 0.2 0.067 987 110 0.08 7.35 988 8110 0.06 −1.34 989 110 0.04 2.00 990 110 0.02 3.696 1000 110 0.008−0.928 1001 9 110 0.006 −3.334 1002 110 0.004 −1.908 1003 110 0.0023.422 1032 110 0.0008 −4.114 1033 10 110 0.0006 −4.604 1034 110 0.0004−6.796 1035 110 0.0002 −5.67

The results given above indicate that by using microcrystallinecellulose particles, the ability of the paint coating to maintain thelower surface of the substrate at a temperature significantly lower thanthat of a substrate having a similar coating containing no celluloseparticles was maintained as the mix ratio was decreased over orders ofmagnitude. This finding is significant as it means that the quantity ofcellulose particles required to achieve the desirable thermal propertiesof the coating is significantly lower than hitherto thought possible. Bybeing able to add lower proportions of cellulose particles with asmaller particle size, it is also possible to develop paints having thedesirable thermal properties for use in areas such as automotive paintswhere very fine particles sizes are required if the paint is to matchthe aesthetic qualities of paints presently used for this application.

Experiments have also been undertaken to determine the effect of varyingthe produced film thickness of coatings at a selected mix ratio. In allof these experiments the cellulose particles used in the coatingcomposition were microcrystalline cellulose particles (Avicel1.02330.0000 produced by Merck Australia Pty Ltd), and these particleswere added to a paint coating composition in the mix ratio referred toin Table 2 and dispersed under high shear breaking the celluloseparticles into cellulose particles having an average dry particle sizeof less than 10 μm. Samples having a coating of the dry thicknessspecified in Table 2 were prepared using these coating compositions (theTest Samples), and the Test Samples tested with Samples A and C asdescribed above, with the heat applied to the surface of the Test Samplehaving the coating and the surface of Sample A having the coating. Therelative inefficiency of these samples in comparison to the referencesample (Sample A) was then calculated as described above. The resultsare set out in Table 2.

TABLE 2 Thickness of Mix ratio Relative Sample Code coating (μm) (g/L)inefficiency (%) 974 90 0.8 4.52 975 90 0.6 −2.38 976 90 0.4 −0.47 97880 1 7.12 979 70 1 5.94 980 60 1 8.99 981 50 1 13.51 982 40 1 20.15 98330 1 23.21 984 20 1 34.24

The results in the above table not surprisingly demonstrate that as thefilm thickness decreases the inefficiency of the coating worsensrelative to the properties of the reference sample (Sample A).

The results do, however, indicate by extrapolation that at a thicknessof about 95 μm the efficiency of a sample having a coating containing 1g/L of microcrystalline particles having an average particle size ofless than 10 μm is the same as the reference sample (Sample A)containing 55 g/L of 50 μm cellulose particles in a layer 270 μm thick.

A series of experiments were conducted to find out the effect of the useof the microcrystalline cellulose in various other coating compositions.In all of the following experiments the microcrystalline particles usedwere obtained from the product Avicel 1.02330.0000 produced by MerckAustralia Pty Ltd. In all the experiments, except the experimentinvolving the window film coating, the cellulose particles were added tothe other coating composition ingredients and dispersed under highshear.

Using a two-pack polyurethane coating (Interthane 80), two samples withcoatings were prepared (the Test Samples). In one Test Sample, a coatingcontaining 0.1 g/L microcrystalline cellulose particles was formed onone 200×300 mm surface of a steel plate. In the other Test Sample, acoating containing no cellulose particles was formed on one 200×300 mmsurface of a steel plate. As indicated above, the other 200×300 mmsurface of the steel plates was coated with a thin layer of conventionalblack paint. Each of the Test Samples was tested together with Sample Aand Sample C as described above with heat applied to the surface of theTest Sample having the coating and the surface of Sample A having thecoating. FIG. 11 shows the results for the Test Sample with a coatingcontaining 0.1 g/L of microcrystalline cellulose particles compared withthe standard reference sample (Sample A) and the all black plate (SampleC). FIG. 12 shows the results for the Test Sample with the coatingcontaining no microcrystalline cellulose particles compared with thestandard reference sample (Sample A) and the all black plate (Sample C).It can be seen that the presence of the microcrystalline cellulose inthe two pack polyurethane coating significantly reduces the temperatureon the non-irradiated side of the sample with that coating compared tothe sample with the coating containing no microcrystalline celluloseparticles.

In another experiment three samples were prepared by applying a coilcoating (plastisol type coil coating) to one 200×300 mm surface of 3steel plates. In one sample (Sample 1), the coil coating had dispersedtherethrough 1 g/L microcellulose particles. In the second sample(Sample 2), the coil coating had dispersed therethrough 15 g/L celluloseparticles. In the third sample (Sample 3), the coil coating did notcontain cellulose particles. The three samples were tested as describedabove with heat applied to the surfaces of the samples having the coilcoatings, and the results are shown in FIG. 13. It can be seen in FIG.13 that the presence of 1 g/L of microcrystalline cellulose dispersed inthe coil coating significantly reduces the temperature on thenon-radiated side of the samples compared to the coil coating withoutmicrocrystalline cellulose and the coil coating with 15 g/L ofmicrocrystalline cellulose.

It can be shown that the dispersion of cellulose particles having anaverage dry particle size of less than 10 μm in all types of paintcoating compositions will have a thermal effect in coatings formed fromthe coating compositions.

Using water based ink, two samples with ink coatings were prepared (theTest Samples) and tested in the test apparatus as described above withheat applied to the surface of the samples having the coating. FIG. 14shows the results of the Test Sample with a water based ink coatingformed from water based ink with 1 g/L of microcrystalline celluloseparticles compared with the standard reference sample (Sample A). FIG.15 shows the results of the Test Sample with a water based ink coatingformed from a water based ink with no microcrystalline celluloseparticles compared with the standard reference sample (Sample A). It canbe seen that the presence of the microcrystalline cellulose in the waterbased ink significantly reduces the temperature on the non-radiated sideof the sample with the coating formed from that ink compared to thesample with the coating formed from the water based ink withoutmicrocrystalline cellulose.

A test was also conducted with a window film coating. Microcrystallinecellulose particles (0.1 g/L) having an average dry particle size ofless than 10 μm were dispersed evenly into a window film material duringmanufacture before application to a glass sheet (Sample 1). A similarglass sheet was also prepared with the same thickness of a similarwindow film containing no microcrystalline cellulose particles (Sample2). These two glass samples were tested in the test apparatus in asimilar manner to that described above with the heat applied to thesurface of the glass sheets having the window film coating, and theresults are shown in FIG. 16. It can be seen in FIG. 16 that theinclusion of the microcrystalline cellulose particles in the window filmmaterial has a thermal effect.

A test was also conducted with fire fighting foam. 1 g/L ofmicrocrystalline cellulose particles (Avicel 1.02330.0000 produced byMerck Australia Pty Ltd) were dispersed evenly into a defined quantityof fire fighting foam under high shear. Two steel plates were preparedwith dams creating a 10 mm high wall surrounding an area 75 mm square atthe center of each plate. One sample (Sample 1) had foam coating with 1g/L of microcrystalline cellulose evenly dispersed in the foam and thesecond sample (Sample 2) had a foam coating with no cellulose particlesadded. The same quantity of foam was added within each dam. The twosamples were tested in the test apparatus in a similar manner to thatdescribed above, with the heat applied to the surface of the samplehaving the foam coating, together with a sample having no foam coating(Sample 3). The results are shown in FIG. 17. FIG. 17 shows that thepresence of the cellulose particles maintained the non-radiated side ofthe sample with the foam coating containing cellulose particles at alower temperature throughout the 40 minute test. The elbow in the curveoccurs when the foam is evaporating to the point with no more liquidpresent. The graph shows that the lower surface of the sample with thefoam coating containing microcrystalline cellulose stays at a much lowertemperature even after all the liquid has evaporated. The graph showsthat it takes approximately twice as long for that sample to reach thesame temperature as the sample with the foam coating with nomicrocrystalline cellulose present. This time difference is verysignificant for fire fighting as the time taken to reach particulartemperatures is critical to fire control and minimizing damage.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

It is to be understood that a reference herein to a prior art documentdoes not constitute an admission that the document forms part of thecommon general knowledge in the art in Australia or any other country.

1. A liquid paint composition comprising 0.0002 g/L to about 0.1 g/L ofcellulose particles having an average dry particle size of less than 10μm dispersed in the composition.
 2. An adhesive composition comprising0.0002 g/L to about 0.1 g/L of cellulose particles having an average dryparticle size of less than 10 μm dispersed in the composition.
 3. A foamcomposition comprising 0.0002 g/L to about 0.1 g/L of celluloseparticles having an average dry particle size of less than 10 μmdispersed in the composition.
 4. A coating formed from a compositionaccording to any one of claims 1 to
 3. 5. An article or structurewherein at least one surface of the article or structure has applied toit a coating formed from a composition according to any one of claims 1to
 3. 6. An article or structure wherein at least one surface of thearticle or structure has applied to it a multiple layer coating with oneor more layers of the coating being formed from a composition accordingto any one of claims 1 to 3.